 In 1912 he moved with his family to a small villa in Wiesbaden, where he spent the next few years as a private scholar.From 1917 he worked as a professor of philosophy at the University of Halle, and in 1930 he retired to Wiesbaden, where he died on 29 December 1950.Ziehen published nearly 450 works on psychology, neurology, anatomy, et al.